It has hitherto been the practice to connect a return circuit from one given hydraulic actuator to another hydraulic actuator whereby to recover and recycle a return fluid from the one actuator to drive the other actuator.
A recovery apparatus known in the art is available to recycle a hydraulic apparatus in which only one hydraulic actuator is included as operable at a time. Unfortunately, it is not applicable to a working machine such as a hydraulic power shovel in which a plurality of hydraulic actuators such as a boom cylinder, an arm cylinder and a turning hydraulic motor are included and where these actuators must be operated simultaneously.
In particular, if in the known apparatus the return circuits of such more than one hydraulic actuators are connected to one separate hydraulic actuator, these return circuits are in effect placed in fluid communication with each other. Then, an attempt to operate one of the actuators in a direction opposite to its return direction may cause all the actuators to so operate simultaneously.
It is accordingly an object of the present invention to provide an actuator return fluid recovery apparatus which is designed to resolve the problem mentioned above.